Polypropylene
A hard, tough polymer of propylene used as a thermoplastic molding material.

Polyurethane
A polymer containing urethane used as plastic, adhesive, paint, rubber, or to form a tough, resistant coating.

Poppy Jasper
An opaque variety of jasper with colors such as brick red, white, brown, and blacks.

Porcelain
Porcelain is often used in jewelry. It is made of fine clay (containing kaolin) which is fired in a kiln to about 2,000?F. The porcelain is covered with a glassy, decorative glaze.

Porosity
Areas of the mold that absorbed some of the casting material leaving the cast object with a rough, granular surface.

Porous
Porous stones have tiny holes in them. These holes allow water, oils, and other substances to penetratethe stone, frequently changing their appearance over time. Many stones are porous, including turquoise.

Posy
An alternate spelling of poesy.

Potash
Any compound containing potassium.

Potassium
A common soft, silver-white, alkali metal element that is only found in nature as a compound with other elements. It is obtained by electrolysis of its common hydroxide, oxidizes rapidly in air and reacts violently with water, and is used in glass making, soap making, in fertilizers, and in many drugs and chemicals.

Poured Glass
Poured glass is a jewelry technique in which glass is suspended within a metal framework. The result is a stained-glass-like effect with translucent glass. The Trifari brooch above is made of yellow glass.

Prase
A translucent leek-green variety of chalcedony varying in color from light green or light grayish-green.

Prase Opal
Prase opal is a green, translucent opal that looks quite similar to chrysoprase (hence the name "prase") or jade. This type of opal is found in Tanzania, Africa. This gem does not display the iridescence found in some opals.

Prayer Ring
A small hinged box secured to a ring which is made to resemble a normal setting, but can be opened to reveal a small space which could be used to hold a small piece of paper with a prayer written on it. See also Poison ring.

Prayer Pendant
A small box worn as a pendant that could be used to hold a small piece of paper with a prayer written on it. See also Poison pendant.

Precious Gemstone
Diamond, ruby, sapphire, emerald and precious opal are the precious stones. Any other rock or mineral is referred to as semiprecious.

Precious Stone
A precious stone (also called a gemstone) is one that is valuable and rare.

Princess Cut
A princess cut is a square-cut stone. This fancy cut is relatively new and is also known as a Quadrillion or Squarillion cut.

Princess Length
A princess length necklace (usually referring to a string of pearls) is 18" long.

Promise Ring
A promise ring is a pre-engagement ring, usually with a relatively small stone.

Prong Set
Prong set stones are held securely in a setting by tiny metal claws.

Prong Setting
A gemstone held in place by small finger-like wires attached to the bezel and bend over the edges of the stone.

Providence
Providence, Rhode Island, is a major US center for costume jewelry, silversmithing, and other metalwork. Many costume jewelry companies are/were located in Providence, including Monet, Danecraft, Barclay, J.J., Lang, Trifari, Speidel, Van Dell, and many, many more.

Prystal
A prystal is an imitation crystal made from translucent, phenolic plastic.

PT.
Pt. is an abbreviation for platinum.

Punches
Pointed tools used for stamping a design on a surface.

Purple Diamond
Purple diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly- compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419.

Pyralin
See French Ivory

Pyrite
Pyrite (also known as fool's gold) is a shiny, metallic mineral that is a form of iron. Marcasite stones come from pyrite.

Pyrolusite
The most common ore of manganese composed of manganese dioxide. It is a soft, iron-black to dark-steel-gray colored mineral and is used extensively in creating brown and green tints of glass.

Pyrope Garnet
Pyrope garnet is the familiar deep red garnet. Red garnet is the birthstone for January. Garnet has a hardness of 6-8 and a specific gravity of 3.5 - 4.3. The formula for garnet is: A3B2(SiO4)3. Pyrope garnet is also called (misleadingly) American Ruby, Arizona Ruby, Australian Ruby, Bohemian Ruby, California Ruby, Cape Ruby, Colorado Ruby, Elie Ruby, Montana Ruby, and Rocky Mountain Ruby.

Pyroxene
Any of a group of crystalline minerals common in igneous rocks containing two metallic oxides . Pyroxene is a silicate of lime and magnesia with sometimes alumina and iron. Though it was named after the Greek words for "fire" and "stranger" because it was supposed to be a rare occurence in igneous rocks, it is actually quite common. It varies in color from white to dark green and black.